This invention relates generally to a shock absorber device for decelerating a machine part by imposing a force on the part over the stroke of the shock absorber device and more particularly to such a shock absorber device of miniaturized construction.
Shock absorbers which force fluid through a restricted orifice to convert the kinetic energy of a moving part into an increase in the thermal energy of the fluid are commonly used on machines. In a typical installation, a machine tool or transfer arm moves back and forth repetitively between separate operating positions and the movement of the tool or arm as it arrives at each position is cushioned and decelerated by a shock absorber positioned on the tool or arm or on the adjacent support structure. Ideally, as the tool or arm is decelerated at each end of its reciprocal movement, the shock absorber acts to exert a relatively constant resistive force against the tool and smoothly decelerates the tool to a stop position in which the piston of the shock absorber has traversed substantially the entire length of the cylinder of the shock absorber so as to take advantage of substantially the entire cushioning capacity of the shock absorber, and the piston comes to a stop just shy of the end of the cylinder so as to avoid bottoming of the piston against the end of the cylinder.
Whereas various metering constructions have been proposed to convert the kinetic energy of the moving part into an increase in the thermal energy of the fluid, none of the prior art metering constructions have provided totally satisfactory operation in shock absorbers of compact or miniaturized construction.
Further, none of the prior art shock absorber constructions have provided simple and totally effective means to ensure that the piston does not bottom against the end of the cylinder and to provide a positive positioning of the machine tool or transfer arm so as to positively and precisely position the workpiece carried by the machine tool or transfer arm to facilitate the performance of a work operation on the workpiece.